Microstructural characteristics of the rheo-diecasting AZ91D magnesium alloy

Take an AZ91D alloy architectural scraper for example,the rheo-diecasting process was implemented by combining a self-developed taper barrel rheomoulding (TBR) machine with a TOYO BD-900V4-T cold chamber die-casting machine.The microstructural characteristics of the components were investigated in different rheo-diecasting processes,and the microstructure formation and solidification behavior of the semi-solid slurry were analyzed.The results show that the process is able to obtain components in which the primary α-Mg particles are fine,spherical or nearly spherical and uniformly distributed.The microstructure of rheo-diecasting components is relatively round and homogeneous when the rotation speed is 700r·min^-1.The primary α-Mg particles have an average size of about 45 μm and a shape factor of about 0.81.Solidification of the alloy melt taking place in the rheo-diecasting process is composed of two distinct stages:primary solidification and secondary solidification.